A study is proposed for the development and characterization of a feline model of human ocular melanoma. Preliminary experiments indicate that injection of a naturally occurring feline sarcoma virus into the eyes of kittens results in the development of uveal melanomas in a high percentage of animals. These tumors bear a close clinical and morphological resemblance to human ocular melanomas. Use of this virus provides the first experimental virally induced melanoma in animals. Tumors thus far developed show a spectrum of cell types consistent with the Callender classification used to categorize human melanomas, and varying degrees of pigmentation. This application proposes to define the developmental events occurring as pigmented cells in the eye undergo malignant transformation, and trace the course of these tumors. The model would appear applicable for the testing of new diagnostic and therapeutic techniques which could be adapted for use with human tumors. This is, in addition, a virus of interest and significance with regard to feline neoplastic and non-neoplastic diseases, and the ocular model offers opportunities for further investigation of the mechanism of natural immunosurveillance against tumors, the immunological response of the host to ocular infection and neoplasia, and the response to immunotherapy.